Introduction: Homopolar Motor With Five Speed Manual Stick-Shift

This video show how to build a homopolar motor that's really's got a five-speed shifter!

The homopolar motor is the simplest design electrical motor in the world. It uses a battery, a neodymium magnet and a wire. Usually, either the copper wire or the magnet rotates. In this case the battery rotates.

Here, I've used a battery, a neo magnet, and a copper wire wrapped around a coat-hanger. The coat-hanger acts as both electrical connection and support for the hanging battery. Coins are used to change speeds of the rotating "battery-plus-change" motor.

I've been recently told that US coins, being non-magnetic, won't work for this Instructable. (Sorry about that!) Perhaps the US coins could be glued together to make it work. Furthermore, some Canadian pennies are magnetic and some are not.

You can order the BEST neodymium super-magnets from K&J Magnetics here.

See more of my homopolar motor videos at :


glaunder (author)2016-01-10

Which specific magnet did you use for this motor? I'd like to know exactly which one before I order it for my Grade 6 science class. Is it axially or diametrically magnetized? Thanks

amnaf (author)2015-11-18

penny, nickel, dime, dollar, 2 dollar

amnaf (author)2015-11-16

which Canadian coins did you use like in money wise

mrfixitrick (author)2014-09-30

Check my other comments about this in the main page. The comments here are jumbled with the timing.

heather.kelleyjones (author)2014-09-29

Im also useing diff size washers bcuz we dont have the coins avalb .. With a 18g copper wire ...??? Help

Have you been able to suspend the battery ok? Can you make the battery spin by using a jumper wire from +terminal of battery to the magnet?

Ive done the jumper cable u suggested and it worked but thats not gonna change the gears??

Havent heard from u yet?

Ok i was able to do a jumper cable like u said but that still not helping in changeing the gears in diff speeds just runs off the batt if i do the jumper thing??

No i have not ? i did your one idea of sanding down the hanger and nothing .. Its not working .. I also did the magnet with just the battery and nothing .. I couldnt find the 1/2 inch thick kind of Neodymium magnet so i got what was alvb the 7 in (18mm by 3mm) battery that comes with three in a pack so im trying the three together so far it will only spin with the copper touching the batt.. ?? Am i still not doing anythhing rt .. And also not useing coins i am useing the washers in diff sz. But makeing it in similar sz of the coins u used in the video???

mrfixitrick (author)2014-09-29

If it runs with the jumper, then there is a contact problem somewhere between the 18 ga copper wire and the coat-hanger, or at the contact point of the copper wire and the washers. Make sure the coils are tight on the coat-hanger.

Is the copper wire perhaps coated with resin and must be sanded too?

mrfixitrick (author)2014-09-29

Make sure the washers will conduct electricity. (they may have a coating to prevent corrosion) Try putting a penny in between the magnet and the washers and make contact with that. If that works, then there may be a contact problem with the washers.

The copper wire must be clean and shiny where it makes contact at each end. The coils must be quite tight on the coat-hanger to make contact.

heather.kelleyjones (author)2014-09-29

im trying to help my son do this project step by step the homopolar 5 speed motor with everything you said that he will need all the material exactly the same and we cant get this thing up and going and i need help what am i doing wrong ..please help project due asap! Thanks

This project is tricky, and i pushed the envelope in regards to all the variables. So, let's find out where the weakness is...

!.) Strong fully-charged battery (NiMH rechargeable 2500 or better MaH)
2.) Strong magnets (N52 strength if possible)
3.) The copper wire must make connection to the coat hanger (coat hanger resin must be sanded off
4.) The point of contact of the coat hanger with battery is critical. Too rounded, and it wont work. Too pointed and battery will fall off.
5.) The angle of the wire contacting the coins is critical.

Perhaps try experimenting with just getting a magnet and battery to spin first, then add the coins.

Let me know what you have done, or send a picture of your setup so I can see what is happening.

Cheers, Rick

swagramp (author)2014-02-03

You can actually use pennies dated before 1981 (thats when they switched over to the zinc alloy).

IshBarrett (author)2013-08-02

Thanks a lot.

IshBarrett (author)2013-08-02

Can any coins which are made of steel, be used to make this motor work?

mrfixitrick (author)IshBarrett2013-08-02

Yes, steel coins or steel washers will work.

pablopsz (author)2012-07-16

I liked his creation, really.

In this video you can see a micro motor homopolar:

Greetings and congratulations

mrfixitrick (author)pablopsz2012-07-16

I like your "cute" motor creation as well...nice work!

vruiz3 (author)2011-08-18

unexplained things #2 homopolar motor with 5 speed shft. :P

technician ace (author)2011-07-17

your idea is a wonderful and revolutionary idea ,sir

Sky_line91 (author)2011-03-04

do you happen to know if this is possible with wires coming from a power source instead of a battery?

mrfixitrick (author)Sky_line912011-03-04

A dc power source will work. It will require up to 5 amps at a couple of volts.

Sky_line91 (author)mrfixitrick2011-03-09

awesome, thanks

divyanshu007 (author)2009-12-29

 how does the movemement of the shifter result in the variation in the speed

mrfixitrick (author)divyanshu0072009-12-30

 The shifter gets moved from coin to coin. Although the various coins have different resistances and magnetic values, the radius of contact of the shifter conductor to the spinning magnetic field is the biggest speed factor. (as long as the conducting coins don't have too much resistance).

Generally, the larger radius coins will spin slower but with more torque. This torque and speed could be calculated using the Lorentz force principles.

Rottom (author)mrfixitrick2011-02-08

would it be possible to just stack different thickness and diameters of the neo mags and apply the gear theory to thus?

mrfixitrick (author)Rottom2011-02-08

Yes, that should work, and produce more torque and rpm as well.

Shingoshi (author)mrfixitrick2010-03-25

I'm guessing that using any circular magnetic surface like one having a conical cross-section would actually give you a variable rate transmission. No more fixed speed shifts. Simply sliding the shifter from one radius to another would immediately change the speed of the device without ever having a discontinuation in rotation.

Xavian-Anderson Macpherson

Shingoshi (author)Shingoshi2010-03-25

Come to think of it. A sewing thimble would work perfectly for testing the idea. Because the less variation in mass, the more accurately one can view the effect of changing the radius alone has. I would flip the cone of the thimble to cover the end of the magnet and extend over the battery. The result will be more stability avoiding the necessity to align coins for proper rotation.


mrfixitrick (author)Shingoshi2010-03-25

 Good idea, I will have to try it one day...or perhaps you should? hehe

Shingoshi (author)mrfixitrick2010-03-25

I just need to find myself some small NbFeB magnets. I'm thinking of a few devices around my house that I could strip apart to acquire the magnets from. So if I do get to do it, I'll definitely post my results here and elsewhere (ie. You Tube).


mrfixitrick (author)Shingoshi2010-03-25

 Interesting concept...A fixed power but variable speed motor with a cone-shaped commutator.

J_gilbert6911 (author)2011-01-03

I am doing this for a science project... somewhat. I am having trouble getting it to work. The thing i dont understand is the coin part. Do you need coins or magnets or both?

The coins are magnetic Canadian coins. They are not necessary, except as a means of altering the speed. (different radius coins)

The magnet is necessary, and must be a powerful neodymium type magnet, found at a place like K& J Magnetics.

Would this type work? 13/16" dia. x 1/16" thick Grade N42 - Nickel Plated

This experiment is tough to do. That 13/16" magnet won't work.

I just tried a 3/4" x 1/16" and it would not hold. 3 or 4 of them stacked will likely work.

A 1/2" x 1/4" N52 magnet will work. I prefer a stronger N52 magnet, and definitely thicker than 1/16", at least 3/8" thickness.

You could stack magnets like coins as well. For example, use a 1", then the 13/16" x 1/16", then a 5/8", 1/2", etc. stacked.

I bought a pack of 10 from K&J Magnetics. Would using several work?

Try an experiment with loading up the battery with as many stacked 13/16" magnets as it can take and still stick well on the hanger.
Then remove one or two magnets for a little less weight. The coins are optional to vary the speed.

The hanger tip where the battery hangs is somewhat critical. It must be rounded and smooth, not a sharp point or edge. The magnetized battery hangs in better that way.

A thicker wire coat-hanger will work better than a thin wire one.

I went to the local home-depot and just gor regular copper-wire. Bought a few D batteries. Then from my science teacher i got a 2", believe its a black hole magnet (like refrigerator magnets but bigger and with a hole in the middle) I wrapped the magnet in tin foil and shaped the wire to fit around it. IT WORKS!!! IT WORKS!!! lol :) So far i have made the heart shape and somewhat of a spiral. Anyone with any ideas for other cool shapes??

Good idea!
I didn't think that would work!

Have a look at this movie that shows wire-formed dragonflies and butterflies using the homopolar motor idea.

camaroboy (author)2010-01-26

how much torque does 1st gear have?

mrfixitrick (author)camaroboy2010-02-03

 Good question. I don't know. 

camaroboy (author)2010-02-02

why does the battery spin faster when the wire touches the coin closest to the magnet/battery?

mrfixitrick (author)camaroboy2010-02-03

 The magnetic field is stronger when closer to the magnet.
 And the radius is smaller, making it run faster.

camaroboy (author)2010-02-02

how come mine doesnt work properly? it only works when touching the magnet. seriously, whats wrong with mine?????????

mrfixitrick (author)camaroboy2010-02-03

 The magnet may need to be stronger.

The coins work best if they are magnetic like Canadian coins or magnetic coins from a magic shop.

camaroboy (author)2010-01-26

how many rpm can the 5 th speed do? 

mrfixitrick (author)camaroboy2010-02-03

5th is about 500 rpm.

About This Instructable




Bio: I am re-inventing myself as an inventor, after too many years as a mechanic! I enjoy learning from Tesla disc Turbines, magnetic motors, and Crystal ... More »
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